#!/usr/bin/env python

# CGIWrapper.py
# Webware for Python
# See the CGIWrapper.html documentation for more information.


# We first record the starting time, in case we're being run as a CGI script.
from time import time, localtime, gmtime, asctime
serverStartTime  = time()

# Some imports
import cgi, os, string, sys, traceback, whrandom
from types import *

if '' not in sys.path:
    sys.path.insert(0, '')

try:
    import WebUtils
except:
    sys.path.append(os.path.abspath('..'))
    import WebUtils
from WebUtils.HTMLForException import HTMLForException

import MiscUtils
from MiscUtils.NamedValueAccess import NamedValueAccess
from UserDict import UserDict

# @@ 2000-05-01 ce:
# PROBLEM: For reasons unknown, target scripts cannot import modules of
#   the WebUtils package *unless* they are already imported.
# TEMP SOLUTION: Import all the modules.
# TO DO: distill this problem and post to comp.lang.python for help.
# begin
import WebUtils.Cookie
import WebUtils.HTTPStatusCodes
# end


# Beef up UserDict with the NamedValueAccess base class and custom versions of
# hasValueForKey() and valueForKey(). This all means that UserDict's (such as
# os.environ) are key/value accessible. At some point, this probably needs to
# move somewhere else as other Webware components will need this "patch".
# @@ 2000-01-14 ce: move this
#
if not NamedValueAccess in UserDict.__bases__:
    UserDict.__bases__ = UserDict.__bases__ + (NamedValueAccess,)

    def _UserDict_hasValueForKey(self, key):
        return self.has_key(key)

    def _UserDict_valueForKey(self, key, default=None):
        return self.get(key, default)

    setattr(UserDict, 'hasValueForKey', _UserDict_hasValueForKey)
    setattr(UserDict, 'valueForKey', _UserDict_valueForKey)

try:
    from cStringIO import StringIO
except ImportError:
    from StringIO import StringIO


class CGIWrapper(NamedValueAccess):
    """
    A CGIWrapper executes a target script and provides various services for
    the both the script and website developer and administrator.

    See the CGIWrapper.html documentation for full information.
    """


    ## Init ##

    def __init__(self):
        self._config = self.config()


    ## Configuration ##

    def defaultConfig(self):
        """
        Returns a dictionary with the default
        configuration. Subclasses could override to customize
        the values or where they're taken from.
        """

        return {
            'ScriptsHomeDir':         'Scripts',
            'ChangeDir':              1,
            'ExtraPaths':             [],
            'ExtraPathsIndex':        1,
            'LogScripts':             1,
            'ScriptLogFilename':      'Scripts.csv',
            'ScriptLogColumns':       ['environ.REMOTE_ADDR', 'environ.REQUEST_METHOD', 'environ.REQUEST_URI', 'responseSize', 'scriptName', 'serverStartTimeStamp', 'serverDuration', 'scriptDuration', 'errorOccurred'],
            'ClassNames':           ['', 'Page'],
            'ShowDebugInfoOnErrors':  1,
            'UserErrorMessage':       'The site is having technical difficulties with this page. An error has been logged, and the problem will be fixed as soon as possible. Sorry!',
            'ErrorLogFilename':       'Errors.csv',
            'SaveErrorMessages':      1,
            'ErrorMessagesDir':       'ErrorMsgs',
            'EmailErrors':            0, # be sure to review the following settings when enabling error e-mails
            'ErrorEmailServer':       'mail.-.com',
            'ErrorEmailHeaders':      { 'From':         '-@-.com',
                                        'To':           ['-@-.com'],
                                        'Reply-to':     '-@-.com',
                                        'Content-type': 'text/html',
                                        'Subject':      'Error'
                                    }
        }

    def configFilename(self):
        """Used by userConfig()."""
        return 'Config.dict'

    def userConfig(self):
        """
        Returns the user config overrides found in the
        optional config file, or {} if there is no such
        file. The config filename is taken from
        configFilename().
        """
        
        try:
            file = open(self.configFilename())
        except IOError:
            return {}
        else:
            config = eval(file.read())
            file.close()
            assert type(config) is type({})
            return config

    def config(self):
        """
        Returns the configuration for the wrapper which is a
        combination of defaultConfig() and userConfig(). This
        method does no caching.
        """
        config = self.defaultConfig()
        config.update(self.userConfig())
        return config

    def setting(self, name):
        """Returns the value of a particular setting in the configuration."""
        return self._config[name]


    ## Utilities ##

    def makeHeaders(self):
        """Returns a default header dictionary containing {'Content-type': 'text/html'}."""
        return {'Content-type': 'text/html'}

    def makeFieldStorage(self):
        """Returns a default field storage object created from the cgi module."""
        return cgi.FieldStorage()

    def enhanceThePath(self):
        """Enhance sys.path according to our configuration."""
        extraPathsIndex = self.setting('ExtraPathsIndex')
        sys.path[extraPathsIndex:extraPathsIndex] = self.setting('ExtraPaths')

    def requireEnvs(self, names):
        """
        Checks that given environment variable names exist. If
        they don't, a basic HTML error message is printed and
        we exit.
        """
        badNames = []
        for name in names:
            if not self._environ.has_key(name):
                badNames.append(name)
        if badNames:
            print 'Content-type: text/html\n'
            print '<html><body>'
            print '<p>ERROR: Missing', string.join(badNames, ', ')
            print '</body></html>'
            sys.exit(0)

    def scriptPathname(self):
        """
        Returns the full pathname of the target
        script. Scripts that start with an underscore are
        special--they run out of the same directory as the CGI
        Wrapper and are typically CGI Wrapper support
        scripts.
        """
        pathname = os.path.split(self._environ['SCRIPT_FILENAME'])[0] # This removes the CGI Wrapper's filename part
        filename = self._environ['PATH_INFO'][1:]
        ext      = os.path.splitext(filename)[1]
        if ext=='':
            # No extension - we assume a Python CGI script
            if filename[0]=='_':
                # underscores denote private scripts packaged with CGI Wrapper, such as '_admin.py'
                filename = os.path.join(pathname, filename+'.py')
            else:
                # all other scripts are based in the directory named by the 'ScriptsHomeDir' setting
                filename = os.path.join(pathname, self.setting('ScriptsHomeDir'), filename+'.py')
            self._servingScript = 1
        else:
            # Hmmm, some kind of extension like maybe '.html'. Leave out the 'ScriptsHomeDir' and leave the extension alone
            filename = os.path.join(pathname, filename)
            self._servingScript = 0
        return filename

    def writeScriptLog(self):
        """
        Writes an entry to the script log file. Uses settings
        ScriptLogFilename and ScriptLogColumns.
        """
        filename = self.setting('ScriptLogFilename')
        if os.path.exists(filename):
            file = open(filename, 'a')
        else:
            file = open(filename, 'w')
            file.write(string.join(self.setting('ScriptLogColumns'), ',')+'\n')
        values = []
        for column in self.setting('ScriptLogColumns'):
            value = self.valueForName(column)
            if type(value) is FloatType:
                value = '%0.2f' % value   # might need more flexibility in the future
            else:
                value = str(value)
            values.append(value)
        file.write(string.join(values, ',')+'\n')
        file.close()

    def version(self):
        return '0.2'


    ## Exception handling ##

    def handleException(self, excInfo):
        """
        Invoked by self when an exception occurs in the target
        script. <code>excInfo</code> is a sys.exc_info()-style
        tuple of information about the exception.
        """

        self._scriptEndTime = time() # Note the duration of the script and time of the exception
        self.logExceptionToConsole()
        self.reset()
        print self.htmlErrorPage(showDebugInfo=self.setting('ShowDebugInfoOnErrors'))
        fullErrorMsg = None
        if self.setting('SaveErrorMessages'):
            fullErrorMsg = self.htmlErrorPage(showDebugInfo=1)
            filename = self.saveHTMLErrorPage(fullErrorMsg)
        else:
            filename = ''
        self.logExceptionToDisk(filename)
        if self.setting('EmailErrors'):
            if fullErrorMsg is None:
                fullErrorMsg = self.htmlErrorPage(showDebugInfo=1)
            self.emailException(fullErrorMsg)

    def logExceptionToConsole(self, stderr=sys.stderr):
        """
        Logs the time, script name and traceback to the
        console (typically stderr). This usually results in
        the information appearing in the web server's error
        log. Used by handleException().
        """
        # stderr logging
        stderr.write('[%s] [error] CGI Wrapper: Error while executing script %s\n' % (
            asctime(localtime(self._scriptEndTime)), self._scriptPathname))
        traceback.print_exc(file=stderr)

    def reset(self):
        """
        Used by handleException() to clear out the current CGI
        output results in preparation of delivering an HTML
        error message page. Currently resets headers and
        deletes cookies, if present.
        """
        # Set headers to basic text/html. We don't want stray headers from a script that failed.
        headers = {'Content-Type': 'text/html'}

        # Get rid of cookies, too
        if self._namespace.has_key('cookies'):
            del self._namespace['cookies']

    def htmlErrorPage(self, showDebugInfo=1):
        """
        Returns an HTML page explaining that there is an
        error. There could be more options in the future so
        using named arguments (e.g., 'showDebugInfo=1') is
        recommended. Invoked by handleException().
        """
        html = ['''
<html>
    <title>Error</title>
    <body fgcolor=black bgcolor=white>
%s
<p> %s''' % (htTitle('Error'), self.setting('UserErrorMessage'))]

        if self.setting('ShowDebugInfoOnErrors'):
            html.append(self.htmlDebugInfo())

        html.append('</body></html>')
        return string.join(html, '')

    def htmlDebugInfo(self):
        """
        Return HTML-formatted debugging information about the
        current exception. Used by handleException().
        """
        html = ['''
%s
<p> <i>%s</i>
''' % (htTitle('Traceback'), self._scriptPathname)]

        html.append(HTMLForException())

        html.extend([
            htTitle('Misc Info'),
            htDictionary({
                'time':          asctime(localtime(self._scriptEndTime)),
                'filename':      self._scriptPathname,
                'os.getcwd()':   os.getcwd(),
                'sys.path':      sys.path
            }),
            htTitle('Fields'),        htDictionary(self._fields),
            htTitle('Headers'),       htDictionary(self._headers),
            htTitle('Environment'),   htDictionary(self._environ, {'PATH': ';'}),
            htTitle('Ids'),           htTable(osIdTable(), ['name', 'value'])])

        return string.join(html, '')

    def saveHTMLErrorPage(self, html):
        """
        Saves the given HTML error page for later viewing by
        the developer, and returns the filename used. Invoked
        by handleException().
        """
        filename = os.path.join(self.setting('ErrorMessagesDir'), self.htmlErrorPageFilename())
        f = open(filename, 'w')
        f.write(html)
        f.close()
        return filename

    def htmlErrorPageFilename(self):
        """Construct a filename for an HTML error page, not including the 'ErrorMessagesDir' setting."""
        return 'Error-%s-%s-%d.html' % (
            os.path.split(self._scriptPathname)[1],
            string.join(map(lambda x: '%02d' % x, localtime(self._scriptEndTime)[:6]), '-'),
            whrandom.whrandom().randint(10000, 99999))
            # @@ 2000-04-21 ce: Using the timestamp & a random number is a poor technique for filename uniqueness, but this works for now

    def logExceptionToDisk(self, errorMsgFilename='', excInfo=None):
        """
        Writes a tuple containing (date-time, filename,
        pathname, exception-name, exception-data,error report
        filename) to the errors file (typically 'Errors.csv')
        in CSV format. Invoked by handleException().
        """
        if not excInfo:
            excInfo = sys.exc_info()
        logline = (
            asctime(localtime(self._scriptEndTime)),
            os.path.split(self._scriptPathname)[1],
            self._scriptPathname,
            str(excInfo[0]),
            str(excInfo[1]),
            errorMsgFilename)
        filename = self.setting('ErrorLogFilename')
        if os.path.exists(filename):
            f = open(filename, 'a')
        else:
            f = open(filename, 'w')
            f.write('time,filename,pathname,exception name,exception data,error report filename\n')
        f.write(string.join(logline, ','))
        f.write('\n')
        f.close()

    def emailException(self, html, excInfo=None):
        # Construct the message
        if not excInfo:
            excInfo = sys.exc_info()
        headers = self.setting('ErrorEmailHeaders')
        msg = []
        for key in headers.keys():
            if key!='From' and key!='To':
                msg.append('%s: %s\n' % (key, headers[key]))
        msg.append('\n')
        msg.append(html)
        msg = string.join(msg, '')

        # dbg code, in case you're having problems with your e-mail
        # open('error-email-msg.text', 'w').write(msg)

        # Send the message
        import smtplib
        server = smtplib.SMTP(self.setting('ErrorEmailServer'))
        server.set_debuglevel(0)
        server.sendmail(headers['From'], headers['To'], msg)
        server.quit()



    ## Serve ##

    def serve(self, environ=os.environ):
        # Record the time
        if globals().has_key('isMain'):
            self._serverStartTime = serverStartTime
        else:
            self._serverStartTime = time()
        self._serverStartTimeStamp = asctime(localtime(self._serverStartTime))

        # Set up environment
        self._environ = environ

        # Ensure that filenames and paths have been provided
        self.requireEnvs(['SCRIPT_FILENAME', 'PATH_INFO'])

        # Set up the namespace
        self._headers = self.makeHeaders()
        self._fields = self.makeFieldStorage()
        self._scriptPathname = self.scriptPathname()
        self._scriptName = os.path.split(self._scriptPathname)[1]

        # @@ 2000-04-16 ce: Does _namespace need to be an ivar?
        self._namespace = {
            'headers':  self._headers,
            'fields':   self._fields,
            'environ':  self._environ,
            'wrapper':  self,
#           'WebUtils':  WebUtils   # @@ 2000-05-01 ce: Resolve.
        }
        info = self._namespace.copy()

        # Set up sys.stdout to be captured as a string. This allows scripts
        # to set CGI headers at any time, which we then print prior to
        # printing the main output. This also allows us to skip on writing
        # any of the script's output if there was an error.
        #
        # This technique was taken from Andrew M. Kuchling's Feb 1998
        # WebTechniques article.
        #
        self._realStdout = sys.stdout
        sys.stdout = StringIO()

        # Change directories if needed
        if self.setting('ChangeDir'):
            origDir = os.getcwd()
            os.chdir(os.path.split(self._scriptPathname)[0])
        else:
            origDir = None

        # A little more setup
        self._errorOccurred = 0
        self._scriptStartTime = time()

        # Run the target script
        try:
            if self._servingScript:
                execfile(self._scriptPathname, self._namespace)
                for name in self.setting('ClassNames'):
                    if name=='':
                        name = os.path.splitext(self._scriptName)[0]
                    if self._namespace.has_key(name):         # our hook for class-oriented scripts
                        print self._namespace[name](info).html()
                        break
            else:
                self._headers = { 'Location': os.path.split(self._environ['SCRIPT_NAME'])[0] + self._environ['PATH_INFO'] }

            # Note the end time of the script
            self._scriptEndTime = time()
            self._scriptDuration = self._scriptEndTime - self._scriptStartTime
        except:
            # Note the end time of the script
            self._scriptEndTime = time()
            self._scriptDuration = self._scriptEndTime - self._scriptStartTime

            self._errorOccurred = 1

            # Not really an error, if it was sys.exit(0)
            excInfo = sys.exc_info()
            if excInfo[0]==SystemExit:
                code = excInfo[1].code
                if code==0 or code==None:
                    self._errorOccurred = 0

            # Clean up
            if self._errorOccurred:
                if origDir:
                    os.chdir(origDir)
                    origDir = None

                # Handle exception
                self.handleException(sys.exc_info())

        self.deliver()

        # Restore original directory
        if origDir:
            os.chdir(origDir)

        # Note the duration of server processing (as late as we possibly can)
        self._serverDuration = time() - self._serverStartTime

        # Log it
        if self.setting('LogScripts'):
            self.writeScriptLog()


    def deliver(self):
        """Deliver the HTML, whether it came from the script being served, or from our own error reporting."""

        # Compile the headers & cookies
        headers = StringIO()
        for header, value in self._headers.items():
            headers.write("%s: %s\n" % (header, value))
        if self._namespace.has_key('cookies'):
            headers.write(str(self._namespace['cookies']))
        headers.write('\n')

        # Get the string buffer values
        headersOut = headers.getvalue()
        stdoutOut  = sys.stdout.getvalue()

        # Compute size
        self._responseSize = len(headersOut) + len(stdoutOut)

        # Send to the real stdout
        self._realStdout.write(headersOut)
        self._realStdout.write(stdoutOut)


# Some misc functions
def htTitle(name):
    return '''
<p> <br> <table border=0 cellpadding=4 cellspacing=0 bgcolor=#A00000> <tr> <td>
    <font face="Tahoma, Arial, Helvetica" color=white> <b> %s </b> </font>
</td> </tr> </table>''' % name

def htDictionary(dict, addSpace=None):
    """Returns an HTML string with a <table> where each row is a key-value pair."""
    keys = dict.keys()
    keys.sort()
    html = ['<table width=100% border=0 cellpadding=2 cellspacing=2 bgcolor=#F0F0F0>']
    for key in keys:
        value = dict[key]
        if addSpace!=None  and  addSpace.has_key(key):
            target = addSpace[key]
            value = string.join(string.split(value, target), '%s '%target)
        html.append('<tr> <td> %s </td> <td> %s  </td> </tr>\n' % (key, value))
    html.append('</table>')
    return string.join(html, '')

def osIdTable():
    """
    Returns a list of dictionaries contained id information such
    as uid, gid, etc., all obtained from the os module. Dictionary
    keys are 'name' and 'value'.
    """
    funcs = ['getegid', 'geteuid', 'getgid', 'getpgrp', 'getpid', 'getppid', 'getuid']
    table = []
    for funcName in funcs:
        if hasattr(os, funcName):
            value = getattr(os, funcName)()
            table.append({'name': funcName, 'value': value})
    return table

def htTable(listOfDicts, keys=None):
    """
    The listOfDicts parameter is expected to be a list of
    dictionaries whose keys are always the same.  This function
    returns an HTML string with the contents of the table.  If
    keys is None, the headings are taken from the first row in
    alphabetical order.  Returns an empty string if listOfDicts is
    none or empty.

    Deficiencies: There's no way to influence the formatting or to
    use column titles that are different than the keys.
    """

    if not listOfDicts:
        return ''

    if keys is None:
        keys = listOfDicts[0].keys()
        keys.sort()

    s = '<table border=0 cellpadding=2 cellspacing=2 bgcolor=#F0F0F0>\n<tr>'
    for key in keys:
        s = '%s<td><b>%s</b></td>' % (s, key)
    s = s + '</tr>\n'

    for row in listOfDicts:
        s = s + '<tr>'
        for key in keys:
            s = '%s<td>%s</td>' % (s, row[key])
        s = s + '</tr>\n'

    s = s + '</table>'
    return s


def main():
    stdout = sys.stdout
    try:
        wrapper = CGIWrapper()
        wrapper.serve()
    except:
        # There is already a fancy exception handler in the CGIWrapper for
        # uncaught exceptions from target scripts. However, we should also
        # catch exceptions here that might come from the wrapper, including
        # ones generated while it's handling exceptions.
        import traceback

        sys.stderr.write('[%s] [error] CGI Wrapper: Error while executing script (unknown)\n' % (
            asctime(localtime(time()))))
        sys.stderr.write('Error while executing script\n')
        traceback.print_exc(file=sys.stderr)

        output = apply(traceback.format_exception, sys.exc_info())
        output = string.join(output, '')
        output = string.replace(output, '&', '&')
        output = string.replace(output, '<', '<')
        output = string.replace(output, '>', '>')
        stdout.write('''Content-type: text/html

<html><body>
<p>ERROR
<p><pre>%s</pre>
</body></html>\n''' % output)


if __name__=='__main__':
    isMain = 1
    main()